Pressure-gage.



W. H. BRISTOL.

PRESSURE GAGE.

APPLICATION FILED MAIL?, 1912.

1,045,779. Patented Nov. 26, 1912.

Immun" a citizen of the United States, and a resif iiNiTnn sTATns raTaNT carica.

WILLIAM H. BRISTOL, 0F WATRBURY, CONNECTICUT, AssIGNoR To THE vBRISTOL COMPANY, 0F WATERBURY, CONNECTICUT, A CoRPoRATIoN or CONNECTICUT.

PRESSURE-GAGE.

inesatto.l

Specification of Letters Patent.

Patented Nov. as, i912.

Application filed March 7, 1912. Serial No. 682,235.

To all whom 'it may concern:

Be it known that I, WILLIAM H. BRISTOL,

dent of '7aterbury, in lthe county of New Haven and State of Connecticut, have mve'nted certain .new'and useful Improvements in Pressure-Gages, of which the following is a specification.

The invention relates to gages for indicating or recording. the pressure under which a particular fluid is placed, and variations thereof; and relates more particularly to that type of pressure gage wherein an indicat-ing or recording arm is actuated by the movement of a suitable member subjected to the uid under pressure, said movement being a function of the change of pressure of said fluid. In such apparatus the indicating or recording arm has, as a rule, -a substantiallyuniform movement; and it is the object of the present invention to so modify the movement of the actuating member that one portion of its range of movement will be markedly different from the rest for equal increments of pressure, forexample-t'he portion ofl the movement with respect to pressures below atmosphere shall be open and occupy one-third of the total range; and the remaining two-thirds shall be contracted and serve to indicate and record relatively high pressures-up to 500 lbs., or more. Gages of such a character are particularly desirable for a number of ur oses for exam le-in connectionwith.

the creosot-ing of wood. In this process, the wood is first subjected to a vacuum treatment to remove the air from the pores, whereupon -the material. is forced therein under extremely high pressure. A gageA of the character herein set forth will be extremely well suited for such purposes, yas a single gage will serve to measure both the vacuum and the high pressure, the former, also, with considerable accuracy because of the open scale possible. v

The nature of the'invention will best be understood when describedin `the accompanying drawings, in which- Figure l'is a front elevation of a recording pressure gage, a portion of the casing being broken away to show the actuating mechanism. Fig. 2 is a detail side elevation; and Fig. 3 is a detail plan of the mechanism. v

Similar characters of reference designate Aembodiment is not located, as is usual, at

the beginning of the graduations of the chart, but some distance upon the same, the chart being graduated in opposite directions from this neutral point; and the arm, in accordance with the present invention is arranged to move in either directionfrom this initial position.

It will be noted from an inspection of the chart that the graduations tothe left of the zero posit-ion are very much more Vopen for l corresponding increments of pressure than those to the right. In the present embodiment, the graduations to the left of the zero represent pressures down to 15 lbs. vacuum, and occupy approximately onethird of the total range of movement of the arm 13,.` The remaining two-thirds portion of the chart is graduated for pressures above atmosphere and to a maximum pressure of 400 lbs.

To effect this unequal or non-uniform movement of the arm with equal increments of pressure, the usual unit actuating mechanism is modified as hereinafter set forth. In the gage shown, the actuating mechanism consists of a well-known type comprising a helical tube 15 closed at the free end and secured at its other end to the mounting, said latter end communicating with a suitable fluid inlet 16. To the free end of the tube 15 is attached, as is usual, the arm 13 which partakes of the contraction or expansion of the helical tube under variations in pressure. This movement of the tube 15 and arm 13 is perfectly free and unrestrained, in one direction, except of course for the resistance offered by the tube 15 itself; and in the present instance, this movement is indicatedy in a direction 'such that pressures below atmospheric pressure will be measured. To provide the contracted portion of the scale for pressure above atmosphere, I have arranged to load the helical g 'p p inserire tube 15 immediately upon :its movementin the oppositev direction from `the neutral point. 'To this end, a coiled spring 17 is.

concentrically mounted' about the free end of the helical tubel, one end of the same being secured to a projecting member 18 ex# tending from the'mounting and the other spectively, upon Vopposite sides of rod 2 0 and.

oppositely disposed.v From a bar 25 extending from the tree portion of the helical tube and through which rod' 20 passes, two pins I g 2.3 and 24am arranged to project and toengage the corresponding notches 21 and 22.

When the helical tube 15 turns-in one direction,these pins move out of their correspondi ing notches and vdo not engage the cross-bar 15.A When ,the movement is 1n the reverse 19,'the resistance to motion of the pointer being merely that inherent in the helical tube direction, however, the pins in their correspending notches engage the cross-bar and "thereby add to the inherent resistance of helical spring 15 that of the spring 17,l

whereby a greater pressure is required to effect anequal movement of the helical tube 15. i

1. The combination with a pressure gage .comprising a helical tube closed at one end and adapted to receive fluid under pressure,

one end of the tube being free and the other fixed, and an indicating or recording arm connected therewith and adapted to move in opposite directions from a neutral point; of

a spring about said helical tube andy adapted to be engaged thereby upon movement ot' the arm on one side of its neutral point.

2. The combination with a pressure gage comprising a helical tube .closed at one end and adapted to receive duid under pressure, i

one end of the tube being free and the other i fixed, and an indicating or recording arm.

connected therewith and adapted to move in opposite directions from a neutral point; of a spring surrounding said helical tube, a cross-bar attached to the said spring, and means extending from the helical tube to engage the said cross-'bar upon movement of the arm on one side of its neutral point.

3. The combination with a' pressure gage comprising a suitable casing, a helical .tube

closedI at one end and adapted to receive fluid under pressure, one end of the tube being free and the other fixed to said casing, an indicating or recording arm connected to the free end of said tubeg'of a coiled spring y about said tube and concentrictherewith, one end of the same being connected to the casing, a'rod extending i'n the axis of said tube andy spring, a cross-bar secured to the tree end ot' said coiled spring and through which said rod passes, said bar being provided upon opposite sides of the rod with oppositely disposed notches, and rods extending from said helical tube to engage the notches of said cross-bar.

Signed at ,New-Yorin in the county of New York, and Stateof New York, this 5th day of March, A. D. 1912l WILLIAM H. BRISTOL. Witnessesz -f l' LAURA E.l SMITH,

FRnnn. F, SCHUETZ.4 l

Copies of this patent may be obtained for ve cents each, by addressing the Commissioner of Patents.

Washington, D. G. 

